One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(5,6)(7,10)(8,9)(11,12)(13,14)(15,17)(16,20)(18,21)(19,24)(22,26)(23,25)(27,28) involution — undirected(6,9)(10,12)(13,15,17,14)(16,23,24,28)(18,21,26,22)(19,25,20,27)(1,2,3,4)(13,16,17,24)(14,19,15,20)(18,27,26,25)(21,23,22,28)(13,16,17,24)(14,20,15,19)(18,27,26,25)(21,28,22,23)(5,7,8,11)(6,10,9,12)(14,15)(19,20)(21,22)(23,28)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.